Textile apparatus

ABSTRACT

In a friction false twisting device of the class comprising a plurality of overlapping rotary discs arranged on parallel axes disposed about a strand path in such manner that a running strand contacts the rim of each disc in turn as it follows a zig-zag spiralling path through the device and is false twisted, one or more of the end discs at the input end of the device, and optionally one or more end discs at the output end, have at least their rim portions of material which has a lesser coefficient of friction with the strand than has the inner discs.

U United States Patent [1 1 3,872,661 Eaves Mar. 25, 1975 [54] TEXTILE APPARATUS 3,702,482 1879?]? lsQhollgl lct al. 57/77.4 ,76 ,l4 1 19 asc e 57/77.4 Inventorl 9 5; r 3,777,467 12/1973 Enneking 57/774 ac es 1e ng an Assignee: Ernest gg & Sons i d, Primary Examiner-Donald E. Watkins MaXXleSfield, England Attorney, Agent, or Firm-Michael S. Striker [22] Filed: Sept. 10, 1973 [21] Appl. No.: 396,114 BSTRACT In a friction false twisting device of the class compris- 301 Foreign Application priority Data mg a plurality of overlapping rotary discs arranged on Se t 8 United Kingdom 418%2 parallel axes disposed about a strand path in such p H manner that a running strand contacts the rim of each disc in turn as it follows a zig-zag spiralling path through the device and is false twisted one or more f [58] Fie'ld 3 77 45 the end discs at the input end of the device, and optionally one or more end discs at the output end, have t least their rim portions of material which has a [56] References Clted a lesser coefficient of fr1ct1on with the strand than has UNITED STATES PATENTS the inner discs. 2,939,269 6/1960 Dobson 57/77.4 3,287,890 11/1966 McIntosh et a] 57/77.4 9 Claims, 2 Drawing Figures TEXTILE APPARATUS This invention relates to friction false twist devices of the kind in which a plurality of overlapping rotary discs are arranged on axes disposed about a strand path in such manner that the running strand contacts the rim of each disc in turn and is false twisted by being rotated by frictional contact with the moving rims as the discs rotate all in the same direction. We have found that by suitably positioning the discs with respect to one another, the strand is caused to travel over each disc rim at an angle inclined to the plane of rotation of the disc so that it is rotated with a substantially pure rolling motion on the disc rim, substantially without slip. In this way, the twist impartation becomes independent of the variations of frictional effect usually associated with friction twisting, in which there has hitherto been substantial slip between strand and friction surface. Consequently, a very precise and positive control of the twisting operation results, giving a surprisingly regular texturing effect in false twist crimping strands such as yarns of synthetic polymeric materials.

A typical device of the kind to which this invention relates comprises three parallel, equiangularly spaced shafts each having a set of three discs with rubber or polyurethane tyres, all of equal radius and equally axially spaced, and arranged so that they overlap one another substantially when viewed axially. The discs are so axially spaced and overlapped that a strand passing through the device follows a zig-zag spiralling path and lies on the friction surface of each tyre at an angle to the direction of motion ofthe surface equal, or substantially equal, to the desired twist angle, and in this man ner the pure rolling motion is achieved.

In order that the strandshould lie at the correct angle on the end disc, the inlet and outlet guides have to be offset from an axial line equidistant from the axes of the three shafts. This, however, can give rise to difficulties in threading-up the device, and it is more convenient from that point of view to locate the inlet and outlet guides upon said axial line, with the result that the strand is not at the correct angle on the end discs.

On the inlet end disc the angle between the strand and the plane of rotation of the disc is greater than the desired twist angle, with the effect that the inlet end disc tends to drive more twist into the strand than the succeeding discs, upon the rims of which the strand lies at the correct angle because all the preceding discs act as correctly located guides (although the first disc may, because the strand is incorrectly positioned, guide the strand not quite correctly on to the second disc). The resulting higher twist will have a tendency to cause slip, thereby re-introducing the irregularities sought to be avoided, although of course to a much lesser extent than with previous friction twisters which operated altogether in the slipping mode.

A somewhat similar situation exists at the outlet end of the device, although in this case the effect of the tendency to impart a higher twist to the strand may cause damage to it.

To overcome these disadvantages the present invention comprises a false twisting device of the kind described in which at least one end disc has a lesser coefficient of friction with the strand than the inner discs.

Preferably each end disc has such a lower co-efficient of friction, and even two discs at one or both ends may advantageously have such a lower co-efficient.

The end disc or discs may have a polished metal rim such as aluminium or steel, or may be of selected surface roughness and/or material.

One embodiment of a friction false twisting device according to the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is an elevation, and

FIG. 2 is a plan.

The friction twisting device shown in FIGS. 1 and 2 comprises nine equal radius discs 11 mounted as sets of three on three equiangularly spaced parallel shafts 12. The discs 11 are equally axially spaced on each shaft 12, and the shafts are so spaced that the discs overlap substantially when viewed axially, as shown in FIG. 2. The shafts 12 are rotatably carried in bearings 13 mounted in a base plate 14, either fixedly mounted or adjustably mounted so that shaft separation can be altered to accommodate strands of differing diameter and requiring different twist levels. Below the base plate 14 the projections of the shafts 12 have wharves or driving pulleys 15 by which, via a belt or band drive, all the shafts can be rotated at the same speed.

The spacing of the discs 11, by shaft spacing and by disc axial separation by spacers (not shown) on the shafts 12, is such that a strand passed through the device lies on the rim of each disc at an angle to the direction of motion of the discs rim equal to the desired twist angle. When so arranged, and the strand suitably guided by inlet guide 17 on to the first disc 11 and by outlet guide 18 away from the last, the device acts in a non-slipping mode, the strand having a pure, or sub stantially pure, rolling motion on the surface of the discs 11. Appropriate positions for the guides 17, 18 are indicated in the drawings in broken lines.

It is desirable, however, to facilitate threading-up, to have the inlet and outlet guides 17, 18 centrally disposed with respect to the strand path through the device, i.e., with respect to the axes of the shafts 12, as shown in full lines in the drawings. With the guides in these positions, the running problems already explained are alleviated if the end discs 11, indicated as 11 (I) (for inlet") and 11(0) (for outlet) have a surface of lesser frictional coefficient with the strand than the inner discs 11. This feature is obtained if disc 11(l) is made at least with a rim of smooth aluminium or stainless steel, for example, or if the whole disc is made of such material, or of other material to have a rim of selected surface roughness which has this feature of less friction with the strand. Further improvement can be obtained by providing that those discs 11 next adjacent the end discs 11(I) and 11(0) also have this feature of less friction with the strand.

It should be ensured, however, that the number of friction discs remaining, provided with the usual rubber or polyurethane tyres, is sufficient to give good control of the twisting effect, for which reason it may be desirable to provide the device with a larger total number of itial to a terminal disc of said plurality with a substantially pure rolling motion over each disc rim portion in succession and at an angle inclined to the plane of rotation of the respective disc, at least the rim portion of at least said initial disc being of material which has a lesser coefficient of friction with the strand than the rim portions of others of said discs.

2. A combination as defined in claim 1, wherein at least said rim portion of said terminal disc is also of said material.

3. A combination as defined in claim 1, wherein at least said rim portion of the disc closest to said initial disc is also of said material.

4. A combination as defined in claim 2, wherein at least said rim portion of the disc closest to said initial disc is also of said material.

5. A combination as defined in claim 2, wherein at least said rim portion of the disc closest to said terminal disc is also of said material.

6. In a friction false-twisting device, a combination comprising a plurality of parallel equi-angularly spaced shafts; and a plurality of sets of rotary discs each having a rim portion, said sets each being mounted on one of said shafts and the discs of each set being spaced axially of the associated shaft, the discs of all sets overlapping one another and forming a zig-zag spiralling path in which a strand to be false-twisted can travel from an initial to a terminal disc of said plurality with a substantially pure rolling motion over each disc rim portion in succession and at an angle inclined to the plane of rotation of the respective disc, at least the rim portion of at least one of said initial and terminal discs being of material which has a lesser coefficient of friction with the strand than the rim portion of others of said discs.

7. A combination as defined in claim 6, wherein said rim portion of said at least one disc is of smooth metal.

8. A combination as defined in claim 7, wherein said metal is steel.

9. A combination as definedin claim 7, wherein said metal is aluminum. 

1. In a friction false-twisting device, a combination comprising a plurality of parallel equiangularly spaced shafts; and a plurality of sets of rotary discs each having a rim portion, said sets each being mounted on one of said shafts and the discs of each set being spaced axially of the Associated shaft, the discs of all sets overlapping one another and forming a zig-zag spiralling path in which a strand to be false-twisted can travel from an initial to a terminal disc of said plurality with a substantially pure rolling motion over each disc rim portion in succession and at an angle inclined to the plane of rotation of the respective disc, at least the rim portion of at least said initial disc being of material which has a lesser coefficient of friction with the strand than the rim portions of others of said discs.
 2. A combination as defined in claim 1, wherein at least said rim portion of said terminal disc is also of said material.
 3. A combination as defined in claim 1, wherein at least said rim portion of the disc closest to said initial disc is also of said material.
 4. A combination as defined in claim 2, wherein at least said rim portion of the disc closest to said initial disc is also of said material.
 5. A combination as defined in claim 2, wherein at least said rim portion of the disc closest to said terminal disc is also of said material.
 6. In a friction false-twisting device, a combination comprising a plurality of parallel equi-angularly spaced shafts; and a plurality of sets of rotary discs each having a rim portion, said sets each being mounted on one of said shafts and the discs of each set being spaced axially of the associated shaft, the discs of all sets overlapping one another and forming a zig-zag spiralling path in which a strand to be false-twisted can travel from an initial to a terminal disc of said plurality with a substantially pure rolling motion over each disc rim portion in succession and at an angle inclined to the plane of rotation of the respective disc, at least the rim portion of at least one of said initial and terminal discs being of material which has a lesser coefficient of friction with the strand than the rim portion of others of said discs.
 7. A combination as defined in claim 6, wherein said rim portion of said at least one disc is of smooth metal.
 8. A combination as defined in claim 7, wherein said metal is steel.
 9. A combination as defined in claim 7, wherein said metal is aluminum. 